1. Field of the Invention
This invention relates to agricultural implements used to apply fertilizer to a subsoil location, and more particularly, to an applicator knife for placing a fluid fertilizer, such as anhydrous ammonia, in a furrow or trench as it is formed. Yet more specifically, the invention relates to an insert which is secured to the shank of a fertilizer knife to form a portion of the leading edge thereof, which insert is especially shaped and fabricated to provide an effective cutting action where stalks, stubble and trash are to be traversed by the fertilizer applicator knife during use.
2. Brief Description of the Prior Art
The use of liquid and gaseous fertilizer materials for enhancing the productivity of soils is a widespread agricultural practice. One of the most widely used fertilizer compositions employed is anhydrous ammonia. This highly nitrogenous fertilizer is applied to the soil by delivering it as a fluid through an elongated tube which extends down the rear side of the shank of a knife utilized to form a furrow or trench in the soil. In the described arrangement, the fertilizer tube is partially protected by its position on the rear or trailing side of the knife blade shank. At the forward or leading side of the knife blade shank, the shank carries a hard metal insert which is welded to the leading edge of the shank, and is configured so as to provide a relatively sharp edge which is capable of cutting through the soil for the formation of the furrow or trench into which the fertilizer is to be deposited.
An important consideration in the construction and utilization of such fertilizer applicator knives is the service life which can be expected of such knives before they must be replaced on the implement to which the knives are bolted during use. In very hard and abrasive soils, the wearing and cutting of the metal forming the applicator blade is severe, and unless some special provision is made to accommodate this abrasion during usage of the tool, the service life becomes unacceptably short, and the expense of replacement at frequent intervals quite high.
In U.S. Pat. No. 4,355,589, assigned to the assignee of the present application, one type of fertilizer applicator knife assembly is illustrated, and such knife assembly carries a wear insert at the leading side of the knife shank. The insert is made of a very hard and abrasion-resistant metal, such as chromium carbide. It is beveled or tapered to a relatively narrow edge at its front or leading edge to provide a cutting action as the knife assembly is forced through the soil during application of the fertilizer.
Other types of hard metal inserts for similar usage at the leading side of a fertilizer applicator knife blade are illustrated in Smith et al U.S. Pat. No. 4,132,181; Stump U.S. Pat. No. 4,201,142; Williams U.S. Pat. No. 4,033,271; Horton U.S. Pat. No. 3,259,087; Johnston U.S. Pat. No. 2,684,617 and Ronck et al U.S. Pat. Des. No. 262,972.
A copy of a brochure which illustrates a typical prior arrangement, as manufactured and sold by the assignee of the present invention, is submitted with the Information Disclosure Statement which is filed concurrently with the present application.